Uses the CUTLASS blackwell_helpers pattern:
- get_smem_store_op creates a SMEM store atom paired with the TMEM load
- make_tiled_copy_D uses the same thread partition as the TMEM load
- Softmax warps write P to sP using the same thread mapping they use for reading S
- MMA warp reads P from sP via pv_mma.make_fragment_A(sP)
- Replaces the zero-fill stub with a proper register→SMEM copy
biondizzle
6aa519d5ec